Research on the Classification of Air-Rail Integrated Hubs in Northwest China Based on Complex Network Theory

With the deepening implementation of the “Transportation Power” strategy, air-rail intermodal transport, as a crucial component of the modern comprehensive transportation system, plays a significant role in promoting regional coordinated development. Based on complex network theory, this study focuses on Northwest China, constructing a freight network model comprising 24 air-rail intermodal nodes. It comprehensively evaluates node importance from four dimensions: degree centrality, betweenness centrality, closeness centrality, and eigenvector centrality. Incorporating indicators such as cargo and mail throughput and high-speed rail connection strength, the study applies systematic clustering to classify hub cities into hierarchical levels. The results indicate that the air-rail intermodal network in Northwest China exhibits a four-tier structure: “Core-Regional-Potential-General”. Xi’an and Urumqi are identified as primary core hubs, Lanzhou and Xining as secondary regional hubs, while the remaining cities are categorized as potential hubs or general nodes based on their centrality scores. The findings provide a theoretical basis and practical reference for the planning, construction, and optimal resource allocation of air-rail intermodal hubs in Northwest China.